We present an all‐inclusive software tool for dealing with the essential core of mathematical and statistical calculations in plant growth analysis. The tool calculates up to six of the most ...fundamental growth parameters according to a purely ‘classical’ approach across one harvest‐interval. All of the estimates carry standard errors and 95 % confidence limits. The tool is written in Microsoft® Excel 2000 and is available free of charge for use in teaching and research from www.aob.oupjournals.org article supplementary data (http://aob.oupjournals.org/cgi/content/full/90/4/485/DC1).
Of the 70 cases of classical biological control for the protection of nature found in our review, there were fewer projects against insect targets (21) than against invasive plants (49), in part, ...because many insect biological control projects were carried out against agricultural pests, while nearly all projects against plants targeted invasive plants in natural ecosystems. Of 21 insect projects, 81% (17) provided benefits to protection of biodiversity, while 48% (10) protected products harvested from natural systems, and 5% (1) preserved ecosystem services, with many projects contributing to more than one goal. In contrast, of the 49 projects against invasive plants, 98% (48) provided benefits to protection of biodiversity, while 47% (23) protected products, and 25% (12) preserved ecosystem services, again with many projects contributing to several goals. We classified projects into complete control (pest generally no longer important), partial control (control in some areas but not others), and “in progress,” for projects in development for which outcomes do not yet exist. For insects, of the 21 projects discussed, 62% (13) achieved complete control of the target pest, 19% (4) provided partial control, and 43% (9) are still in progress. By comparison, of the 49 invasive plant projects considered, 27% (13) achieved complete control, while 33% (16) provided partial control, and 49% (24) are still in progress. For both categories of pests, some projects’ success ratings were scored twice when results varied by region. We found approximately twice as many projects directed against invasive plants than insects and that protection of biodiversity was the most frequent benefit of both insect and plant projects. Ecosystem service protection was provided in the fewest cases by either insect or plant biological control agents, but was more likely to be provided by projects directed against invasive plants, likely because of the strong effects plants exert on landscapes. Rates of complete success appeared to be higher for insect than plant targets (62% vs 27%), perhaps because most often herbivores gradually weaken, rather than outright kill, their hosts, which is not the case for natural enemies directed against pest insects. For both insect and plant biological control, nearly half of all projects reviewed were listed as currently in progress, suggesting that the use of biological control for the protection of wildlands is currently very active.
Mussels, such as
Mytilus edulis, are common keystone species on open coasts and in estuaries and are frequently used in environmental monitoring programmes. Mussels experience a wide range of ...environmental conditions at these locations, including rapid changes in salinity and physical disturbance (both natural and from aquaculture practices).
This paper addressed the hypothesis that reduced salinity will lower mussel blood immune function and influence mussel blood metabolic responses, and that this will in turn increase the susceptibility of mussels to other stresses such as physical disturbance. To test these hypotheses, experiments were conducted in controlled laboratory tank conditions and mussel blood was analysed using a combination of metabolic fingerprinting with FT-IR and immunological assay techniques.
Reducing seawater salinity to half that of normal caused a significant reduction in several measures of immune function, including the concentration of haemocytes, percentage of eosinophilic haemocytes and phagocytosis. Mechanical shaking of mussels for 10 min caused a reduction in the level of respiratory burst activity. However, there was no evidence of additive or interactive effects of lowered salinity with shaking on the immune response. Analysis of mussel blood metabolic fingerprints revealed differences in response to half salinity (
vs. full salinity) but there were no detectable effects of shaking. Increasing frequency and magnitude of flood events at coastal sites due to climate change could lead to longer, and more frequent, periods of reduced salinity. The potential impact on the immune function of this keystone species within or near estuaries could have knock-on effects on the wider ecosystem including altered nutrient cycling, changes in biodiversity and aquaculture production.
Background Induction of endogenous regulatory T (Treg) cells represents an exciting new potential modality for treating allergic diseases, such as asthma. Treg cells have been implicated in the ...regulation of asthma, but the anatomic location in which they exert their regulatory function and the mechanisms controlling the migration necessary for their suppressive function in asthma are not known. Understanding these aspects of Treg cell biology will be important for harnessing their power in the clinic. Objective We sought to determine the anatomic location at which Treg cells exert their regulatory function in the sensitization and effector phases of allergic asthma and to determine the chemokine receptors that control the migration of Treg cells to these sites in vivo in both mice and human subjects. Methods The clinical efficacy and anatomic location of adoptively transferred chemokine receptor–deficient CD4+ CD25+ forkhead box protein 3–positive Treg cells was determined in the sensitization and effector phases of allergic airway inflammation in mice. The chemokine receptor expression profile was determined on Treg cells recruited into the human airway after bronchoscopic segmental allergen challenge of asthmatic patients. Results We show that CCR7, but not CCR4, is required on Treg cells to suppress allergic airway inflammation during the sensitization phase. In contrast, CCR4, but not CCR7, is required on Treg cells to suppress allergic airway inflammation during the effector phase. Consistent with our murine studies, human subjects with allergic asthma had an increase in CCR4-expressing functional Treg cells in the lungs after segmental allergen challenge. Conclusion The location of Treg cell function differs during allergic sensitization and allergen-induced recall responses in the lung, and this differential localization is critically dependent on differential chemokine function.
Many parasites of seasonally available hosts must persist through times of the year when hosts are unavailable. In tropical environments, host availability is often linked to rainfall, and ...adaptations of parasites to dry periods remain understudied. The bird-parasitic fly Philornis downsi has invaded the Galapagos Islands and is causing high mortality of Darwin's finches and other bird species, and the mechanisms by which it was able to invade the islands are of great interest to conservationists. In the dry lowlands, this fly persists over a seven-month cool season when availability of hosts is very limited. We tested the hypothesis that adult flies could survive from one bird-breeding season until the next by using a pterin-based age-grading method to estimate the age of P. downsi captured during and between bird-breeding seasons. This study showed that significantly older flies were present towards the end of the cool season, with ~ 5% of captured females exhibiting estimated ages greater than seven months. However, younger flies also occurred during the cool season suggesting that some fly reproduction occurs when host availability is low. We discuss the possible ecological mechanisms that could allow for such a mixed strategy.
Four bioassays for the light environment, obtained from three Veronica species, were critically compared for 20 field sites using instantaneous electronic readings as a standard. Among total ...chlorophyll (leaf dry weight and leaf area basis), specific leaf area and the chlorophyll a to chlorophyll b ratio, the last provided the most realistic correlation, increasing with available light. The ratio is physiologically flexible, is least influenced by soil magnesium status or water availability, and is dissociated from patterns imposed by changes in leaf density.
This study analysed the dynamics of cell production and extension, and how these were affected by applied gibberellic acid (GA3), during internode development in dwarf peas (Pisum sativum L. cv. ...Meteor). Image analysis was used to obtain cell number and length data for entire cell columns along the epidermis, the two outermost cortical layers, and the pith, from internode 7, over a time period covering the whole of the internode's growth phase. For a few days following the inception of an internode at the shoot apex, little further growth occurred, and there was no significant effect of GA3 on cell division or cell extension. The subsequent growth of the internode was stimulated more than fourfold by GA3 as a result of the production of more than twice the number of cells, which were twice as long. At least 96.5% of the cells of the mature internode were actually formed within the internode itself during this period of growth, demonstrating that the internode cells themselves represent the morphogenetic site of response to GA3. Mitoses and cell extension occurred along the full length of the internode throughout its development. The daily changes in cell numbers were modelled by the Richards function, and manipulations of the fitted functions to reveal time trends of absolute and specific cell production rates were performed for each stem tissue. The increase in cell numbers in the + GA3 plants was brought about by an increase in the rate of cell production, over a shorter time interval; specific cell production rates declined continuously from initial rapid rates in the + GA3 epidermis and pith, but declined more slowly in the cortex. The control (-GA3) epidermis and cortex cells exhibited a constant specific cell production rate (i.e. purely exponential) for several days. Cell extension rates were calculated so as to compensate for the size-reduction effects of concurrent cell division. These calculations confirmed that 'real' cell extension rates were higher in the + GA3 internodes. Models of the cellular controls of internode growth, based on the estimated dynamics of cell division and extension, are discussed.
Eukaryotic genomes are packaged into nucleosomes, which are thought to repress gene expression generally. Repression is particularly evident at yeast telomeres, where genes within the telomeric ...heterochromatin appear to be silenced by the histone-binding silent information regulator (SIR) complex (Sir2, Sir3, Sir4) and Rap1 (refs 4,5,6,7,8,9,10). Here, to investigate how nucleosomes and silencing factors influence global gene expression, we use high-density arrays to study the effects of depleting nucleosomal histones and silencing factors in yeast. Reducing nucleosome content by depleting histone H4 caused increased expression of 15% of genes and reduced expression of 10% of genes, but it had little effect on expression of the majority (75%) of yeast genes. Telomere-proximal genes were found to be de-repressed over regions extending 20 kilobases from the telomeres, well beyond the extent of Sir protein binding and the effects of loss of Sir function. These results indicate that histones make Sir-independent contributions to telomeric silencing, and that the role of histones located elsewhere in chromosomes is gene specific rather than generally repressive.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Standard controls and best practice guidelines advance acceptance of data from research, preclinical and clinical laboratories by providing a means for evaluating data quality. The External RNA ...Controls Consortium (ERCC) is developing commonly agreed-upon and tested controls for use in expression assays, a true industry-wide standard control.
Standards for Microarray Data Ball, Catherine A.; Sherlock, Gavin; Parkinson, Helen ...
Science (American Association for the Advancement of Science),
10/2002, Letnik:
298, Številka:
5593
Journal Article
PDF
